1. Field of the Invention
The present invention is directed to a vehicle security system which is remotely controllable. More particularly, the vehicle security system of the present invention is a microprocessor controlled system which allows transmitting units to be sold as separate units from the receiving units and allows each receiving unit to be used with several transmitters. The present invention also allows for the personalized setting of a shock level detector, allows for the device to be selectively operable to be automatically armed or manually armed, and allows for selective operation in a full current sensing mode or a shock and current integration sensing mode.
2. Discussion of the Background
Remotely controlled automobile security systems are well known in the art. Conventional remote automobile security systems operate such that an operator of a vehicle can remotely activate or turn on an automobile security system after leaving the vehicle and can deactivate or turn off the automobile security system upon returning to the vehicle, by a hand held remote transmitter.
When the vehicle is armed, a conventional automobile security system may operate to detect a situation in which a voltage dip on the automobile battery is sensed or in which current begins to flow through the ignition system of the automobile without the automobile security system having been deactivated, which may be indicative of an unauthorized operation of the automobile. At this point, the automobile may be disabled and an alarm may be activated. Further, conventional remote automobile security systems may operate in conjunction with a shock sensor which will output a signal to an alarm if a shock which exceeds a predetermined threshold is detected by the shock sensor when the automobile security system has been activated. In this way, shocks occurring as an intruder attempts to enter an automobile without authorization will cause an alarm signal to issue if the automobile security system has been activated. Other conventional automobile security systems may feature glass breakage transducers to sense a glass breakage event and issue an alarm after detecting such an event.
However, known remote automobile security systems suffer from several drawbacks. For example, the conventional transmitting unit and receiving unit must be precoded to operate with the same code words, and so a particular transmitter unit can only be used with a particular receiving unit. Moreover, in conventional automobile security systems, shock level sensitivity cannot be easily varied by an operator. Therefore, certain ambient conditions (e.g., thunder, heavy trucks passing by, etc.) may be sufficient to generate disturbances to trigger a conventional shock sensor having a low threshold, resulting in a false alarm. If the operator of the automobile could selectively set the threshold at which the shock sensor is activated, the occurrences of such false alarms could be minimized.
A further drawback of conventional automobile security systems is that they have limited flexibility in the manner in which they become armed and feature simple shock detectors which only detect shocks exceeding a single predetermined threshold.
A further drawback of conventional automobile security systems is that in certain vehicles a voltage or current sensing circuit cannot be utilized and only a shock sensing circuit can be utilized. That is, as noted above, several automobile security systems feature voltage or current sensing circuits in which a voltage dip or current flow is sensed while a security system is activated to trigger the indication of an unauthorized intrusion into the automobile and to cause the automobile to be disabled and/or an alarm to be sounded. For example, when a vehicle door is opened while a security system is activated, the current which flows to activate the inside lights of the vehicle can be detected to trigger an alarm signal.
However, in certain automobiles on the market today current will periodically flow through the automobile electrical system when the car is not being operated. For example, certain vehicles feature mechanical clocks which must be periodically wound. This is automatically done in such vehicles by periodically allowing a current to flow to a motor in the clock which then activates a winding mechanism to wind the clock. This winding operation will often be done while the automobile is not being operated. An automobile security system featuring a current sensing device cannot be utilized in an automobile with such a feature since the current flowing to wind the clock would be detected by the automobile security system and would be read as an unauthorized operation of the vehicle, resulting in the automobile being disabled or in the triggering of an alarm.